[sdiy] InfectionInstruments Newsletter No. 005

[David Hughes]

Hello,

It's been a busy two weeks and work on the General Development System has
continued at a very healthy pace. 

Membership of the discussion group continues to grow and, as of last night,
we've reached 46 members. A warm welcome to all of those newcomers to the list.

In the last newsletter (004, 02-Aug-02) we were able to demonstrate the
prototype version of Zeit playing sequences from memory with the MIDI velocity
modified by a software-derived low frequency oscillator. 

Since then, Zeit has expanded quite a bit and the prototype system now features
an eight channel potentiometer board, rotary encoder inputs, four switches and
the all-important tempo LED. These were all constructed on stripboard and they
look a bit rough and ready but they at least give us the opportunity to develop
software very rapidly.

There are a collection of video snaps over on the web page for those who are
interested. The quality of these snaps is a major disappointment to us and we'll
be investing in a decent quality digital camera in a couple of weeks.

So, what can Zeit do at the moment? The best way to demonstrate this is to have
a listen to some of the samples over on the InfectionInstruments web pages (http://www.infectionmusic.co.uk).

Zeit is able to play eight note sequences on one MIDI channel, with
transposition, synchronised to an external MIDI clock. We ran the prototype from
a Yamaha RM1x Rhythm Re-sequencer at it's maximum tempo of 300 bpm for two hours
and Zeit was still playing properly with no stuck notes or unusual system
problems. 

When we first started to experiment with the eight pitch knobs it became
immediately obvious that, such was the coarse resolution of the potentiometers,
finding an accurate pitch was quite difficult. The next step was to write the
force-to-scale routines and to limit the effective range of the pitch knobs in
software. The video snaps illustrate force-to-scale and transposition in action.
The sequencer is set up to play a major scale so that, when a knob is turned,
the resulting MIDI Note numbers always fall in a major key. Press a key on the
MIDI keyboard and the sequence is transposed but the notes played still remain
in a major key. My favourite example of this technique is the ChurchOrgan sample.

I've uploaded seven samples in total which should demonstrate some of the
capabilities of the sequencer. Have a listen and let me know what you think.

That's all for now. I'm on holiday in two weeks time so the next newsletter may
be a couple of days late.

Best wishes
   David

-- 
Infection Music
http://www.infectionmusic.co.uk
http://www.mp3.com/tbassuk